Variable-speed changing gear



Feb. 19, 1952 s Q RENNERFELT 2,586,260

VARIABLE-SPEED CHANGING GEAR Filed Nov. 13, 1950 INV ENTOR ATTORNEYS.

vlllllllillwllllllllll Patented Feb. 19, 1952 VARIABLE-SPEED CHANGING GEAR Sven Bernhard Rennerfelt, Goteborg, Sweden Application November 13, 1950, Serial No. 195,376 In Sweden November 14, 1949 5 Claims. 1

The present invention relates to a variable speed changing gear of the type in which two friction discs-located substantially in a common plane and secured to separate shafts and having a .thickness decreasing towards the periphery cooperate with two friction wheels which are forcibly pressed against the friction discs and are rockably mounted on a gear shaft displaceable between said separate shafts. The object of the invention is to provide an improved construction in which the pressure between the friction wheels and the friction discs varies according to the momentum of the shafts.

Some embodiments of the invention are illustrated in the accompanying drawing, in which:

Fig. 1 is a section through a gear according to the invention. Fig. 2 is a section through a detail of a gear according to another embodiment, and Fig. 3 shows in a similar way as Fig. 2 a modified form of detail of Fig. 1. Fig. 4 is a section, taken on line IV-IV in Fig. 1.

Referring to Fig. 1, reference numeral I denotes the driving or primary shaft of the speed changing gear on which shaft there is rotatably mounted a friction disc 2. Numeral 3 denotes the secondary or driven shaft, having keyed onto it a friction disc 4, both friction discs 2 and 4 having a thickness decreasing from the centre and outwards. Two friction wheels are rockably mounted by means of ball bearings 6 on an intermediate shaft 1,' which is journaled in ball bearings 8 in a diagrammatically shown frame I8, which is displaceable between the shafts I and 3 by means of a screw I9 in order to vary the gear ratio.

On the shaft I there is provided a cam 9, which actuates an oil pump I of the piston type, which by means of a conduit II is connected to a house I2 which is secured to the .gear casing and surrounds the shaft I in order to convey oil under pressure to a channel Ia in the rotating shaft and from which also leads a conduit comprising a tube 21 which is sliding telescopically in a bore in the house I2 and projects from a house I2a which conveys oil to a channel 'Ia in the shaft I.

The channel Ia opens in a cavity in a member I4 which is keyed onto the shaft I and in which are slidably mounted six pistons I the outer ends of which being formed like wedges cooperating with corresponding recesses in the friction disc 2. It will be understood, that the pistons I5 tend to move inward in their bores when the shaft I is rotating. In one of the bores there is provided anopening I6 through which oil can escape to the oil store I'I at the bottom of the gear casing and which opening is controlled by the pertaining piston.

vThe channel 'Ia opens in a cylinder I3 coaxial with and keyed onto the shaft 'I in which cylinder slides a piston 26 supporting one of the ball bearings 6.

When the shaft I is rotated the pump I0 de- 2 livers oil through the conduit II to the house I2 and'channel Ia. As the oil at first can escape through the opening I6 the pistons I5 can easily move inward until the opening I6 is at least `partially covered by its piston. Then the oil pressure increases until an equilibrium is attained in which the axial pressure .from the disc 2 exerted upon the pistons I5 is balanced by the oil pressure in the cavity behindv said pistons. In this position of the pistons I5 and disc 2 is forced to rotate together with the shaft Il and it is evident that the value of the oil pressure corresponds to the momentum which is necessary for rotating the disc 2.

As the cylinder I 3 communicates with the house i2 the piston 26 tends to move outward, thereby pressing the friction wheels 5 against the discs 2V and 4, when the oil pressure increases. The force is dependent on the oil pressure and thus varies according to the momentum.

If the shaft I is driven with a constant momentum the pressure between the friction discs and friction wheels must be greater when the wheels make contact with the disc 2 near its centre than when the contact occurs near the periphery of said disc. On its way from the conduit II to the opening I6 the oil has to pass f an opening 28 'which is located such as to be covered by the tube 2I when the shaft 'I is moved to its end position nearest the shaft I. The oil then must pass through a throttling opening 29 whereby the oil pressure in the cylinder I3 becomes greater than the pressure in the cavity in the member I4.

In Fig. 1 there is shown a safety valve 30 which is controlledvby the slidable tube 2l in a similar way as the opening 28 so that it is uncovered when the shaft 'I is moved toward its upper end position in which the shaft 3 is driven with high speed.

Fig. 4 is a section on line IV-IV in Fig. 1 and shows an end View of the member I4 with its six pistons I5 and their wedge-formed ends, the edges of the wedges being directed radially. In Fig. 3 is shown a modied form of the member I4 in Fig. 1 comprising a member 25 with only one piston 23 corresponding to that piston in Fig. 1 which controls the opening I6. In Fig. 3 the piston controlled opening bears numeral 24. The outer end of the piston 23 is formed like a wedge cooperating with sloping faces 22 in a recess in the hub of the disc 2| (corresponding to disc 2 in Fig. l)

In Fig.. 2 is shown another embodiment of the driving parts of the gear. The peripherally spaced pistons I5 in Fig. 1 are here substituted by a piston 33 having a ring-shaped cross-section and. being slidable in a cylinder 34 keyed onto the shaft I. The cylinder 34 communicates with -th`e oil pump through channels 36,' 31 and 38. A pin 35 prevents the piston 33 from rotating relatively to the cylinder 34.

The outer end of the piston 33 is provided with wedge-shaped,projections cooperating with corresponding recesseszinzthe friction disc 3| (corresponds to disc 2 in Fig. 1). At increasing momentum the piston 33 moves inward and thereby a flange on the piston actuates a valve 39 so that this valve tends to close anopen'ing'lleading oil from the cylinder 34. The ,oil ow-isthus throttled and the oil pressure'increases.

What I claim is:

1. A variable speed changing gear-comprising in combination, a casing, a primary shaft and a secondary shaft mounted in said casing, a friction disc on said primary shaft, a second frictionf'disc onA said secondary shaft, said discs being located substantially in a vcommon-plane andhaving-affthickness decreasing towards the periphery,

`a-gearfsha'ft'located A'between said primar-y `and said-'secondary `shaft in parallel .relation thereto and being 'mounted in 'a'frame displaceable betweensaidprimaryand'said secondary shaft, two friction wheels rockably mounted on said -gear sha'ftin engagement `with the lateral faces `of 'said i=fraction discs, fluid-.actuated `means for forcingl said wheels vagainst said discs, source vof`fluid under'pressure communicating with said uid "actuated 'means andmeans'responsive to the transmitted momentum to vary the-.pressure offsaid iiuid-in orderftoincrease-.thepressure between vsaid `wheels and discs at Yincreasing fmomentum.

:2. A-variable speed changing gear comprising in-fcombination, .a casing, a primary shaft and a secondary shaftimounted vin saidcasing, a friction disc on saidiprimary-shaft, a second frictiontdisc on -said'secondary shaft, said discs being locatedV substantially in=a common-.plane and having-athickness decreasing towards theperiphery, agear shaftlocated between-said primary and said secondary shaft in parallel relation thereto and being mounted in a framedisplaceable between said-.primaryand said'secondary shaft, two friction wheels, rockably Amounted on said .gear shaft in engagement With:the flateral-,faces` of ,-saidfriction discs, fluid-actuated :means for .forcing said wheels, against said discs,V asource of fluidunder pressure 'communicating with said 4fluid actuated means, one of said friction discs being rotatably mounted `on 4its ishaft, vcoupling means on said last-mentioned shaftv tn transmitthe .rotation of theshaft to said-frotatablyemounted friction disc, said Vcoupling means -being yieldable to .permit relative movement .between -usaid rotatably mounted disc and its shaft in dependance upon themomentum-.of that shaft, and means responsive to vrelative movement between said shaft andits .rotatably mounteddisc to vary thepressureo`f said =iiuid in order to Aincrease thepressure between said wheels and ,discs at. increasing momentum.

'3. ,-A variable speedchanging gear comprising in combination, a casing, .a primary shaft and a secondaryshaft ,mounted Yin said casing, a friction-disc on-said primary shaft, a vsecond Afriction disc-on said secondary-shaft@ said, discs being located substantially in a common plane and having a thickness decreasing towards the peripheryfagear -shaftlocated between said primary and saidsecondary shaft inparallel relation thereto andbeing mountedin a frameV displaceable "between :said primary Yand f said :secondary shaft, twofriction wheels'rockably mounted 'on said fgear shaftin-engagement with the lateral Vfaces of -said friction discsffluid-"actuated means for forcingfsaid wheels against-said discs, one of said friction discs being rotatably mounted on its shaft, cam means on said rotatably mounted disc, at least onepiston slidably mounted on said last-mentioned shaft and constructed and arranged to cooperate with said cam means and actuated by the pressure fluid, an outlet opening for saidpressure fluid, said outlet opening being controlled bysaidpiston such that its area dccreases at increasing momentum.

4. A variable-speed changing gear comprising `in combination, a casing, a primary shaft and 'friction wheels rockably mountedon saidgear shaft in engagement with the lateral'faces'ffsaid friction discs, duid-actuated' means for "forcing said wheels againstsai'd discs, a sourcefoflfiuid under pressure communicating with said fflui'd actuated *means and means responsive tto the transmitted vmomentum to vary the pressure -o`f said fluid in order to'increaseithe pressure ibetween said wheels and discs at increasing niomentum, and'means connected`to= said lgearsfshaft constructed `and arranged to increase :the r`4fiuld pressure in the fluid-actuated'imeanswvhen Said shaft is in its end position nearest the'primary shaft.

5, A variable speed changing fgear comprising in combination, a casing, a primary `shaftfand a secondary shaft mountedin' saidfcasing;^africtlon disc on said primary `shafira 'secondfrlctionfdisc on said secondaryshaft, Vsaid Avdiscsrbeing 'located substantially in common plane andhavinga thickness decreasing towards the periphery, Ia gear shaft located between said v`primary and saidsecondary shaft in parallelirelation thereto and being Vmountedin a frame idisplaceable'between said primary 'and saidsecondary shaft, two friction wheels rockably mounted yon said gear shaft in engagement'with-the lateralf-aces of --said friction discs, iiuid-actuated means 'i for forcing said wheels against said discs, a source of fluid underpressure ,communicating with :said fluid actuated means, and means responsive to the transmitted momentum'to varythegpressure of said 'fluid in' order to'r increasethe pressure `between said wheels and discs Vvat increasing 1m0- mentum and means connectedtoVv saidy gear'shaft, saidlast named means comprising va throttling device for the fluid nowi actuated by ,theldisplacementof the gearshaft so-that -the fluid pressure increases in thel duid-,actuated Ameans -when isaid shaft is initsend positionlnearestthe:primary shaft.

SVEN BERNHARD R-ENNEREELT.

REFERENCES 'CITED The following references are -of recordiin the le of this patent:

UNITED kS'IATES TPATE'NTS Number Name ADate '766,438 Gardner Aug. 2,1904 849,051 Churchward `Apr. '2, 1907 2,509,940 Rennerfelt May'30;i950

,FOREIGN `EEA'IENIITS Number Country Date 143,686 Switzerland Nov."30,"130 

